1. Field of the Invention
The present invention relates to a rotary cutter capable of consecutively recovering chips resulting from cutting when the rotary cutter is surrounded by a chip container. In particular, the invention relates to a rotary cutter which is suitable for a machine tool provided with an automatic tool exchange apparatus, for example, a machining center.
This application claims priority of Japanese Patent Application HEI 9-267017 which is hereby incorporated by reference.
2. Discussion of the Background
An example of such a rotary cutter having a chip-repelling mechanism is the one disclosed in Japanese Patent Publication No. 3-281114.
The rotary cutter will be described with reference to FIG. 7.
A rotary cutter 1, for example, a face milling cutter, includes a plurality of tips 3 provided at a given distance on the top periphery of a cutter body 2, as shown in FIG. 7. A chip guide section 4 is mounted on the top periphery of the cutter body 2, and the chip guide section 4 faces to the cutting faces of the top cutting edges and the peripheral cutting edges of the tips 3 with a space therebetween. An arbor 5 is fitted into the base of the cutter body 2 and coaxially fixed with a bolt 6. Also, a substantially cylindrical chip container 7 is arranged on the peripheral area of the cutter body 2, and the base of the chip container is mounted on the arbor 5 with a bearing 8 therebetween so as to be relatively rotatable. An outlet 9 for recovering the chips is formed on the peripheral area of the chip container 7.
The arbor 5 connects the cutter body 2 to a main spindle 12 supported by a spindle head 11 of a machine tool 10, and is mounted on the main spindle 12 with a pull-stud 14 being pulled in toward the rear end of the main spindle while its taper shank 13 is fitted into the main spindle 12. A key seat 15 of the arbor 5 is brought into engagement with a key 12a of the main spindle 12, and thus the rotation of the main spindle 12 is transmitted to the cutter body 2. The arbor 5 includes a grip 16 which can be brought into engagement with a tool exchange arm (not shown in the drawing) of an automatic tool exchange apparatus provided on the machine tool 10.
A constrained mechanism 17 which is connected to the bearing 8 is integrally formed on the base of the chip container 7, and the constrained mechanism 17 is provided with a fitting hole 18 which is opposed to the spindle head 11 of the machine tool 10. A positioning pin 20 is slidably inserted within the fitting hole 18 with a compressed spring 19 underneath. The tip of a bolt 22, which is horizontally screwed into the constrained mechanism 17 toward the center of the arbor, protrudes and is retained in a groove 20a of the positioning pin 20, and thus, the moving range of the positioning pin 20 along the axis of the cutter body 2 is restricted.
Also, a fitting recess 23 is formed on the spindle head 11 for receiving a tip 20b of the positioning pin 20 while the arbor 5 is mounted on the main spindle 12. A retainer 20c which horizontally protrudes toward the center of the cutter body 2 is formed in the middle of the positioning pin 20, and the retainer 20c is engageable with a recess 24 provided on the periphery of the arbor 5.
Accordingly, when the arbor 5 is not mounted on the main spindle 12 of the machine tool 10, the positioning pin 20 of the constrained mechanism 17 moves up until the tip of the bolt 22 is brought into engagement with the lower end of the groove 20a by means of elasticity of the spring 19, and the retainer 20c is brought into engagement with the recess 24 of the arbor 5 whereby the relative rotation between the arbor 5 and the chip container 7 (constrained mechanism 17) is resisted. Also, when the arbor 5 is mounted on the main spindle 12, the tip 20b of the positioning pin 20 is inserted within the fitting recess 23 of the spindle head 11, the positioning pin 20 is pushed down into the fitting hole 18 against the force of the spring 19, and the tip of the bolt 22 is brought into engagement with the upper end of the groove 20a. In such a state, the retainer 20c is detached from the recess 24 of the arbor 5, and the cutter body 2 is relatively rotatable toward the fixed chip container 7.
As shown in FIG. 8, a table 27 of the machine tool 10 for placing a material 26 to be cut may include a mechanism having a conveyor 28 for transporting chips in parallel to the material 26 to be cut in the relative feeding direction of the cutter body 2. In such a machine tool 10, the outlet 9 of the chip container 7 is set to face toward the conveyor 28, and cutting is performed while the cutter body 2 (or the material 26 to be cut) is being moved parallel to the conveyor 28.
During the cutting process, while the arbor 5 is mounted on the main spindle 12, if the top cutting edges and the peripheral cutting edges of the cutter body 2 are pressed onto the material 26 to be cut, and are moved, for example, in the direction of an arrow A in FIG. 8 for cutting, the chips produced by each cutting edge are forcibly led into the chip container 7 through a space between the chip guide section 4 and the cutting faces of the tips 3, and then, they are removed toward the inner peripheral area of the chip container 7 by means of a centrifugal force of the rotating cutter body 2, repelled out of the outlet 9 onto the conveyor 28, and received by a recovery box or the like (not shown in the drawing).
In the machine tool 10, the key 12a and the fitting recess 23 of the spindle head 11 are in predetermined positions, and, on the other hand, in the rotary cutter 1, the key seat 15 of the arbor 5 and the positioning pin 20 provided on the constrained mechanism 17 are in predetermined positions. However, the machine tool 10 may include a key 12a and a fitting recess 23 which are arranged in positions that angularly deviate from the predetermined positions of the key seat 15 and the positioning pin 20. In such a case, unless, for example, manually, the retainer 20c of the positioning pin 20 is detached from the recess 24 of the arbor 5 and the chip container 7 is relatively rotated for positional adjustment, the positional pin 20 cannot be fitted into the fitting recess 23 of the spindle head 11 while the key seat 15 of the arbor 5 is fitted into the key 12a of the main spindle 12.
Also, for example, because of the above-mentioned configuration angle, while the positioning pin 20 of the constrained mechanism 17 is fitted into the fitting recess 23 of the spindle head 11, the outlet 9 of the chip container 7 may not face the conveyor 28 for recovering chips on the table 27. In such a case, an efficient recovery of chips by the conveyor 28 cannot be performed.